1. Field of the Invention
The present invention relates to a pneumatic tire provided with four main grooves extending in the tire circumferential direction in its tread part. Specifically, the present invention relates to a pneumatic tire which has a secured driving stability on dry road surfaces and concurrently which has an improved snow performance without worsening its pattern noise.
2. Description of the Related Art
Various proposals have been so far made on a type of pneumatic tire which is provided with four main grooves each extending in the tire circumferential direction in its tread part, and the four main grooves partition the tread part into: a center land part; paired intermediate land parts located with the center land part being interposed in between; and paired shoulder land parts located with the center land part and the paired intermediate land parts being interposed in between (see Japanese patent application Kokai publications No. 2005-297880, No. 2003-211921 and No. 2003-146016, for example).
Increasing the number of groove in the tread part can possibly improve the snow performance of such pneumatic tire, yet, at the same time, its pattern noise as well as its driving stability on dry road surfaces tends to be deteriorated. For this reason, it is demanded that the tire of the foregoing type should have an improved snow performance without inviting these problems.